Reenforced insulating roof slab



Feb. 4, 1936. l J, BECKWITH 2,029,352

REENFORCED INSULATING ROOF SLAB Filed April l5, 1932 BY @hdi/MM ATTORNEY Patented ret. l4,.'1936 d 2,029,352

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2,029,352 REENFORCED iNsULA'rmG noon SLAB Charles J. Beckwith, Brooklyn, N. Y., assignor Vto Johns-Manville Corporation, New York, N.. Y., a corporation of New York Application April 15, 1932, Serial No. 605,367-

7 Claims. (Cl. 10S- 1) This invention' relates to a reenforced insulatorvwood ber board, that is light in Weight and ing roof slaby or panel. The invention relates effective in thermal insulation. Compositions especially to a. reenforced unit comprising an comprising asbestos rlbers or mineral wool may insulating core, units of facing material on each e150 be used. Thus, there may be used such com- Side 0f the insulating 001e. and inwardly disposed positions in which the fibers are bonded into 5 reenfOl'Cing ribs 01' members semi-rigid slabs or blocks by means of a binder,

` A panel fOl use. S215. iu the 100f 0f a factory such4 as starch or asphalt. When the insulating building ShOuld be DOH-COIlodible. adapted t0 core is senil-rigid, it serves to brace and thereby carry a substantial load, resistant to breaking strengthen the assembled panel. If this func- 10 by shock, and should beprovlded With an eX- tion is not desired in the panel, loose felting ma- 10 terior that is non-porous or impervious and, for terial, such as iibers that are not bonded together, some purposes, should be adapted to be washed, may be used as the insulating core. to be polished. to present a pleasing appearance The facing material 3, 4, or 5 is juxtaposed on without decoration, and/or to preserve this pleaseach side of the insulating core and,is adhered ing appearance on long exposure to the atmosthereto by the adhesive 2. Afacing material that 15 Dhele- F01 sOme purposes. the panel Should he is preferred at this time is an asbestos and Portleproof and thermal insulating. Y land cement sheet that is in wide use commercial- An object of the present invention is to pro- 1y, Sueh sheet material may be made by mixing vide a structural'unit or panel that meets the approximete1y one part by weight of asbestos above requirements. Other objects and advanbers with one of Portland cement and Water, to 20 tages Will appeal as. the desel'lpllOn Of the ini/enform a sludge, forming` the mixed materials into FFlCE tion progresses. a layer that is relatively thin in proportion to its A preferred embodiment of the invention is length and breadth, highly compressing the layer illustrated in the dIaWiug iu Which t to densify it and to expel excess water, and allow- Fig. 1 shows aperspe'etive view of an insulating l ing the sheet thus formed to harden. Such a 25 panel in which the inwardly disposed reenforcing product is rigid, in' the sense that the terni is members 0r ribs are cotinuous bars of a modiused herein, that is, substantially rigid although fled Z'Shapey Y resiliently yieldable under heavy loading of sheets Fig- 2 ShOWS a perspective VleW 0f all embOdlof common commercial thicknesses, strong, stonement of the'invention in which the panel has ,fa like, ineombustible, and non-porous to the extent 3o greater thickness of facing material on the side that water does not pass through it readily, althat is to be under tensionv than on the other though the sheet may absorb some moisture side that is to be compressed when the panel is from a humid atmosphere, is non-corrodible, and loaded during use. The reenforcing members may be polished and washed, with the producmay be smell I-beams and the Panels may have tion of a, pleasing surface that does not undergo 35 `not only side but also end edges provided with substantial change on exposure to air. other Ship-13D onst'ucl'fionfacing materials, having as many of the proper- Fig, 3 ShOWS uperspecl'fve VeW lil Which WOOden ties of the asbestos and cement board as may be strips are usedas the reenforcing members. This desired in a, panel for a, given use, may be used.

ligure ShOWS also a metllOd 0f assembling EWO However, the asbestos and cement board is pre- 4o panels et their side edges. ferred at this time, not only because of the prop- Fig. 4 shows a perspective view of an assembly erties given, but also because strong, rigid sheets adapted fol use as a IOOf. This g'ure shows also of such board may be had in thicknesses that are `the preferred methodoi assembling the panels at not excessive from the standpoint of weight in theifsde edges, namely, in a Ship-lap joint. s a building. structure, and at a cost that is satis- '45, v

In the various iigures, like reference characters factory Vdenote like parts- Thus, I is an insulating core It will be understood that, in the structure or inwardly disposedinsulating member. It may shown in Fig.l 1, the facing members are spaced consist of onev or more plies or layers of insulatand xed approXimateIy but not exactly in preing matelal- YIf more than One layer is used. the established position with respect to each other; 50 various layers are advantageously adhered to When a load is applied to a face of such a unit, each other. as, f0l' eXample. by means 0f a Conto give exing. there arisesl compression of the tinuous film of casein or other suitable adhesive facing member to which the load is applied and 2. The insulating material is suitably in pretension of the opposite facing member.

formed semi-rigid form, such as cane ber board The facing material may have different thick- 55 nesses on thel two sides of the panel. Thus the layer of facing material Il that is to be the upper side in a roof and that is to be under compression when the roof is loaded, may be thinner than the facing material on the opposite side which is under tension when the roof is loaded. This is especially desirable when the facing material used is one that has a substantially greater compression than tensile strength, as is the case with asbestos and Portland cement boards. Since such boards have sometimes ten times as great compression as tensile strength, it will be evident that much different thicknesses may be used on the two sides of the panel, if it is desired that the facing material on the two sides should .fail vunder about the same load. Thus the facing material that is to be under tension may be substantially thicker, say, two to nve or ten times as thick as the other layer of facing material. However, the upper layerof facing material, say, in a roof structure, should Anot be so thin as to permit its being punched through or broken by a concentrated load. v

The reenforcing bars are in spaced relationship to each other and may extend lengthwise or crosswise in the panel. The lengthwise arrangement illustrated is preferred at this time.

These reenforcing bars or members may be constructed ofsteel or other rigid, non-brittle metal and may have a modified Z-shape, as illustrated at 6, or other suitable shape, such as that of a small I-beam I suitably formed by spot- Welding together the backs of channel irons at intervals, as at 8. A-s illustrated, the web memas by case-hardened, self-tapping screws 9 passing l through preformed holes in the facing material at intervals and through iianges of the reenforcing members, to increase the rigidity of the strucure.v

In the modification shown in-Fi'g. 3 the reen- `forcing members or bars II'I consist of a. more resilient material such as wood. Such members are. adapted to be flexed substantially without breaking and to return to their original position, to' a larger extent than is the case when the reenforcing members are of `the metal type illustrated in the other gures. It should be understood, however, that the steel members, for

example, are also somewhat springy or resilient, that is, are adapted to be/'exed to a certain extent vwithout being permanently deformed to the full extent of the temporary flexure.

The wooden reenforcing strips may be secured to the facing material by means of wood screws II. Further, the wooden strips may be seated at one or both of their outer edges in channel irons or other supporting members I2. In this: case, the securing means or screws I I may pass through the facing material and the supporfng means and-into the wood. Y

The edges of a panel, suitably on at least two opposite edges, may be closed by reenforcing strips I3. These serve to face the insulating core at its edges and thereby protect the -edge ofthe insulating core and to reenforce the panel. Further, these edge-closing strips may take the shiplap form shown at I9, which adapts the panels to be assembled as illustrated in Fig. 4. Or the` edge strips may be provided with a notch I4, corresponding to a similar notch or groove in another sheet, and adapted to enclose therewith a spline member I5. The spline member may be of the same material as the edge strip. Thus, if the edge strip is wood, the spline member may also be of wood, such. as hardwood.

The insulating core as indicated may be of one or more thicknesses of insulating material. One thickness only isshown in Fig. 1. Two thicknesses joined along the cement layers 2 are illustrated in Fig. 2. Three thicknessesjoined along the cement layers 2 are illustrated in Fig. 3. In the roofV assembly shown in Fig. 4, only a purlin I6 of the supporting substructure is given. The purlin extends transversely to the length of the panels and permits the abutment of ends of panels in aline over the face of the purlin. Adjacent panels abut at their side edges along the ship-lap joint I9, ior example. It will be understood that there may be employed any conventional .substructure suitable for vsupporting large panels of building material of the weight and size that are to be used. The purlin I6 is suitably attached, as by screws II, to panels I8 of the ty/peof the present invention. The screws or other suitable fasteners secure the purlin to the reenforcing members at both ends of the panel, as shown in Fig. 1. A man on the roof, for example, is supported by the steel reenforcing members and is thus kept from falling through, even though the panel cracks. on one or more of its faces.' The assembly of panels is covered with a conventional roofing exterior, as, for example, by a built-up roong comprising roofing paper 20, suitably in a plurality of layers, such as three or more, adhered to the upper surface ofthe panels and to each other by means of adhesive layers 2I, composed suitably of an asphalt mopping of usual composition, applied in a usual manner.

the underlying panels but also provides some shock absorption and distribution of concentrated loads, thereby reducing somewhat the danger of breakage of the thin facing unit 4 by shock Aor bysharply localized overloading.

Panels of the construction described may be made of various dimensions. Thus there has been made a panel 4 by 8 feet with an insulating core of l inch insulating lumber, Z-bar reenforcing members extending lengthwise ofthe sheet, the Z-bars having inchweb 'and 1%, inch flanges and being spacedon 12'inch centers. The asbestos and cement boards, constituting the fac- These were attached to the reenforcing members by nat head machine screws on 12 inch centers.

Also, the facing sheets were adhesively secured to the two faces of the insulating core -by means of a casein adhesive. The reenforcing members and v,insulating core extended continuously between the inside surfaces of the facing sheets.

This panel had an over-all thickness of 1.48

-inches and weighed 7.2,pounds per square'foot.

When submitted to test, the panel showed surprising properties. Supported by beams at positions '1 feet apart and subjected to concentrated. loading, the 7 foot span failed by cracking of the lower unitof facing material, at 1,665

The built-up roofingv Aserves not onlyV to prevent access of water to -o Ving members on either side, were 1A inch thick.

pounds total load. The maximum deection at break was 0.85 inches. When the load was removed from the sheet that had failed, the panel returned partly to its original position, so that the maximum permanent deflection was 0.48

inches.

, Similar tests were made.` on a panel in which cured plies of 1A inch insulating lumber. The

over-al1 thickness was 1.82 niches and the weight per square foot 6.8 pourids. The breaking load for a 'I foot span of this panel was found to be 1,665 pounds also. The maximum deiection at l break was 0.87 inches and the maximum permanent deflection, after removing the load from the broken panel, was only 0.26 inches.

The advantages of structural insulating panels that will withstand such loads and yet will be deflected so little, even on breaking, are obvious.

The panels have other advantages in addition to those that have been mentioned. The composited panel is. less rigid than a sheet of equal thickness composed solely of the facing material. When the composited panel is flexed there is less stretching of the face that is under ten-l sion, for a given amount of iiexure, than when the panel is constructed throughout of solid, rigid material of the type used as the facing of the composite.

The panelsare light in weight in proportion t their strength. They can be installed in a structure easily and' may be supported in long spans. The thermal insulating properties ofthe panel have been mentioned. In this connection it should be observed that the reenforcing members may have low heat conducting capacity. Ii the reenforcingmembers are wood, the specific thermal conductance is low as compared to the spe-f cific conductance of a metal. Furthermore, when the reenforcing members are composed of material that is high in specific thermal conductance, sayof steel, the area of cross section of such members may be so small that the actual heatcarrying capacity is low. Furthermore, the facing material of the preferred composition is not such as to transmit heat very readily to the reenforcingmembers. For example, the specific thermal conductance of asbestos and Portland cement sheets is low as compared to that of sheet steel. If

the facing materialwere constructed o f metal, such as steel, and the metal facing were directly in contact with metal reenforcing ribs extending from one side to the other, there would be substantial capacity for transference of heat along the facing material to the ribs and then through the ribs to the opposite side of the panel. l

Since mamf variations from the illustrative details that havev been givenmay bev made without departing from the Iscope of the invention, it is intended that the invention should be limited only by the terms of the claims.

What I claim is:

1. A panel comprising an inwardly disposed thermal insulating member, stone-like facing units juxtaposed on leach side of the insulating member, and spaced reenforcing bars extending between the inside surfaces of the facing units, the insulating member and also the reenforcing bars being secured to the facing units.

2. A panel comprising an inwardly disposed thermal insulating member, non-porous, rigid, non-corrodible, flreproof facing units juxtaposed on each side of the insulating member, spaced reenforcing bars extending between the inside surfaces of the facing units, and ship-lap reenforcement closing at least two opposite edges of the panel.

3 3. 1n a thermal insumting stmctural unit, of

large load carrying capacity, comprising an insulating core and rigid facing material of greater compression than tensile strength adhered to both faces of the core, the improvement comprising facing material of substantially greater thickness on the face of the unit that is to be under tension than on the side that is to be compressed under load.

4. In a thermal insulating structural unit, of large load carrying capacity, comprising an insulating core and rigid facing material of greater compression than tensile strength adhered to both faces of the core, the improvement comprising facing material of thickness at least twice as great on the face of the unit that is to be under tension as on the side that is to be compressed under load.

5. A thermal insulating, water-tight, fire-resistant roof assemblyadapted to carry a substantial load, said assembly comprising a supporting substructure, panels, of the kind vdescribed in -claim 3 and containing as the facing material preformed sheets of compressed and hardened composition of asbestos and Portland cement, supported by the substructure, and built-up roofing overlying the said panels, the said roofing preventing the entrance of moisture into the assembly and also minimizing the danger ofA localized overloading of the facing material adjacent thereto. 6. A structural unit, adapted to support a substantial load applied to a face thereof, comprising a core material and strong facing members of like material, of greater strength under compression than under tension, disposed over and adjacent to the opposite faces of the said material and xed in approximately preestablished position with respect to eachother, the facing member that is to be under tension being of substantially greater thickness than the facing member that is to be under compression when the unit is loaded. '7. A structural assembly including a supporting substructure, panels,lsupported at opposite ends on the substructure, comprising a preformed insulating core, rigid facing units disposed on each side of the insulating core, and inwardly disposed reenforcing members, and means securing the said reenforcing members to the substructure at both ends of the panels, the said core and reenforcing members extending continuously between the inside ofV the said facing units and the core panels. Y

' CHARLES J. BECKWITH. 

